We undertook a best-evidence synthesis on the incidence, risk factors and prevention of mild traumatic brain injury. Methods: Medline, Cinahl, PsycINFO and Embase were searched for relevant articles. After screening 38,806 abstracts, we critically reviewed 169 studies on incidence, risk and prevention, and accepted 121 (72%). Results: The accepted articles show that 70-90% of all treated brain injuries are mild, and the incidence of hospitaltreated patients with mild traumatic brain injury is about 100-300/100,000 population. However, much mild traumatic brain injury is not treated at hospitals, and the true population-based rate is probably above 600/100,000. Mild traumatic brain injury is more common in males and in teenagers and young adults. Falls and motor-vehicle collisions are common causes. Conclusion: Strong evidence supports helmet use to prevent mild traumatic brain injury in motorcyclists and bicyclists. The mild traumatic brain injury literature is of varying quality, and the studies are very heterogeneous. Nevertheless, there is evidence that mild traumatic brain injury is an important public health problem, but we need more highquality research into this area.

We searched the literature on the epidemiology, diagnosis, prognosis, treatment and costs of mild traumatic brain injury. Of 428 studies related to prognosis after mild traumatic brain injury, 120 (28%) were accepted after critical review. These comprise our best-evidence synthesis on prognosis after mild traumatic brain injury. There was consistent and methodologically sound evidence that children's prognosis after mild traumatic brain injury is good, with quick resolution of symptoms and little evidence of residual cognitive, behavioural or academic deficits. For adults, cognitive deficits and symptoms are common in the acute stage, and the majority of studies report recovery for most within 3-12 months. Where symptoms persist, compensation/litigation is a factor, but there is little consistent evidence for other predictors. The literature on this area is of varying quality and causal inferences are often mistakenly drawn from cross-sectional studies.Descriptive: 98.65% made good recovery, 0.25% died. All with LOC <15 minutes had good outcome. 5.9% developed seizures

The WHO Collaborating Centre for Neurotrauma Task Force on Mild Traumatic Brain Injury performed a comprehensive search and critical review of the literature published between 1980 and 2002 to assemble the best evidence on the epidemiology, diagnosis, prognosis and treatment of mild traumatic brain injury. Of 743 relevant studies, 313 were accepted on scientific merit and comprise our best-evidence synthesis. The current literature on mild traumatic brain injury is of variable quality and we report the most common methodological flaws. We make recommendations for avoiding the shortcomings evident in much of the current literature and identify topic areas in urgent need of further research. This includes the need for large, well-designed studies to support evidence-based guidelines for emergency room triage of children with mild traumatic brain injury and to explore more fully the issue of prognosis after mild traumatic brain injury in the elderly population. We also advocate use of standard criteria for defining mild traumatic brain injury and propose a definition.

These definitions provide standards that may improve future comparisons of low back pain prevalence figures by person, place and time characteristics, and offer opportunities for statistical summaries.

The elimination of compensation for pain and suffering is associated with a decreased incidence and improved prognosis of whiplash injury.